POST-TROPICAL HELENE
Helene is officially post-tropical centered in Kentucky but producing catastrophic flooding across portions of the southern Appalachians.
Over portions of the central and southern Appalachians, Helene is expected to produce additional rainfall amounts of 1 to 2 inches leading to widespread total rainfall accumulations of 6 to 12 inches, with isolated totals exceeding 20 inches. This rainfall will result in catastrophic and potentially life-threatening flash and urban flooding, along with record level river flooding in many instances. Numerous significant landslides are expected in steep terrain across the southern Appalachians. Elsewhere, 1 to 3 inches of rainfall is expected across portions of the Ohio Valley through Sunday evening.
HURRICANE ISAAC
Category 1 Hurricane Isaac is moving over the open waters of the Atlantic and will not threaten land. Hurricane-force winds extend outward up to 15 miles from the center and tropical-storm-force winds extend outward up to 90 miles.
TROPICAL STORM JOYCE
Like Isaac, Joyce does not pose a threat to land. Joyce is moving toward the northwest near 13 mph over the central Atlantic.
Maximum sustained winds have increased to near 50 mph with higher gusts. Some additional strengthening is possible through early Saturday, followed by gradual weakening through early next week. Tropical-storm-force winds extend outward up to 70 miles from the center in the northern semicircle.
Potential Development in the Western Caribbean
An area of low pressure could form over the western Caribbean Sea by the middle of next week. Environmental conditions are expected to be conducive for slow development thereafter while the system moves generally northwestward, potentially entering the Gulf of Mexico by the end of next week.
Formation chance through 48 hours...low...near 0 percent.
Formation chance through 7 days...low...30 percent.
Potential Development in the Eastern Tropical Atlantic
An area of low pressure could form over the eastern tropical Atlantic by the early to middle part of next week. Environmental conditions are expected to be conducive for slow development thereafter while the system moves generally northwestward at 10 to 15 mph.
Formation chance through 48 hours...low...near 0 percent.
Formation chance through 7 days...low...30 percent.
